Pulsed laser deposition grown La0.3Ca0.7Fe0.7Cr0.3O3-δ thin films on yttria-stabilized zirconia substrates for fundamental electrochemical energy conversion studies

•La0.3Ca0.7Fe0.7Cr0.3O3-δ thin films deposited by pulsed laser deposition.•25 nm thick films are dense and uniform with a surface roughness of 0.2 nm.•The thin films are shown to be amenable to fundamental electrochemical studies. La0.3Ca0.7Fe0.7Cr0.3O3-δ (LCFCr) perovskites, normally deposited as a powder-based ink to form porous electrode layers, have been shown to be exceptional catalysts for the electrochemical splitting of CO2 to form CO at one electrode and O2 at the other during electrolysis in solid oxide cells, while also being highly active and stable under fuel cell conditions. This work constitutes the first report of thin film deposition of LCFCr via pulsed laser deposition on a 001-oriented yttria-stabilized zirconia substrate, used to simulate the ionically conducting electrolyte in operating cells. The primary goal of this work was to determine fundamental LCFCr properties and performance metrics without complications from morphology effects. Scanning Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy analysis confirmed that oriented, dense, uniform, and smooth films with a thickness of ca. 25 nm and a RMS surface roughness of 0.2 nm are grown at 700 °C from a stoichiometric LCFCr target, while containing all the components of LCFCr in their expected oxidation states. These thin films have allowed the determination of the oxidation states of the redox active species on the electrode surface. Moreover, the preliminary electrochemical response of the LCFCr thin films in an air environment is shown to mimic the trends observed in more common highly porous LCFCr electrodes, thus arguing for a similar reaction mechanism and kinetics per real surface area.